The extent and control of avian influenza in Canada.

The large variety of influenza A virus types circulating among wild birds in their northern breeding grounds represents a menace to the Canadian poultry industry. The principal victims of avian influenza in the past were turkeys, exceptionally affected were ducks, but never chickens. Influenza in Ontario turkeys reached a peak incidence at the end of the 60's, then it declined steadily to isolated infrequent infections. The decline is attributed to efforts made to avoid contact between domestic turkeys and wild birds. The prospect of controlling avian influenza by vaccination is discounted, and it is recommended to place more emphasis on isolation of the turkeys and improved sanitation on the farms.